Consider the equation below. (If an answer does not exist, enter DNE.) f(x) = 9 sin(x) + 9 cos(x), 05 x 27 (a) Find the interval on which f is increasing. (Enter your answer using interval notation.) Find the interval on which f is decreasing. (Enter your answer using interval notation.) (b) Find the local minimum and maximum values of f. local minimum value local maximum value (c) Find the inflection points. ( x, y ) = ( (smaller x-value) ( x , y ) = ( larger x-value) Find the interval on which fis concave up. (Enter your answer using interval notation.) Find the interval on which fis concave down. (Enter your answer using interval notation.)